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C. E. SORIBNER. TELEPHONE EXCHANGE TESTING APEAEATUS.

N0. 504,250. .Patented Aug; 29, 1893',

UNITED STATES CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN PATENT OFFICE.

ELECTRIC COMPANY, OF SAME PLACE.

TELEPHONE- EXCHANGE TESTING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 504,250, dated August 29, 1893.

Application tiled June 1, '1889. Renewed December 13, 1892 Serial No. 456,012. (No model.)

To all whom it may concern.-

Be it known that I, CHARLES E. SORIBNER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Telephone-Exchange Testing Apparatus, (Case No. 207,) of which the followingis a full, clear, concise, and exact description, reference being had tothe accompanying drawings, forming a part of this specification.

My invention relates to te1ephone exchange apparatus and its obj ect is to provide for testing at one board to determine whether a line` wanted is in use at any other board while the same operators telephone may be used when desired to listen out or to determine whether any pair of subscribers who have been connected have hung up their telephones.

My invention consists in the arrangement of the circuits of the subscribers telephone outfit to include the subscribers te1ephone battery in the circuit of the line when the telephone is off the hook while the same battery also serves to operate the transmitterand induction coil of the subscribers set.

My invention further consists in the arrangement of the circuits of the switchboard key-table including n the operators telephone outfit whereby an operator may test at any of the test rings by means of her own test battery to determine whether any line is in use or test at any plug in the circuit of two connected subscribers independently of her test battery to determine whether the subscribers have hung their telephones upon the hook; the operator is thus enabled by listening at her telephone and manipulating the proper apparatus to determine whether a line is connected at another board and also whether two subscribers who have been connected have hung up their telephones. y

My invention is illustrated 1n the accompanying drawings in Which?.-

Figure lis a diagram showing three grounded telephone lines connected each with a different switch on each of three multiple switch boards and each through its individual annunciator to ground, a subscribers outfit being shown in detail at one of the subscribers station and the operators outfit at one of the switchboards. Fig. 2 is a sectional view of one of the connecting plugs.

The subscribers outfit at station 1 consists of the usual telephone signal bell transmitter, the local battery et, however, being connected in derived circuit with the main line so that in addition to its ordinary work of furnishing current for the transmitter and primary of the induction coil it sends current at the same time over the main line whenever the telephone is removed from the switch as shown at said station l. y

All the local batteries of the subscribers stations are arranged to send current over the telephone lines thereof to the central office in the same direction. I have shown the zinc pole connected to line toward the central office.

As shown at board 2 the operator is pro- 1 vided with a te1ephone and transmitter and a battery b in a normally open circuit, this battery having its copper pole toward the connecting plugs c d. When, therefore, the test battery b is closed to any line having its local battery@ closed to line the two batteries will be in' a direction to reinforce one another and this is one object of having the local batteries a, of all the stations connected in the same direction with reference to their lines respectively.

` Between the test battery b andithe telephone I have connected a iexible branch or cord e having a suitable terminal f; this branch being connected on the ground side of the batteryb and hence when the said battery is open at the key h the telephone of the operator will not be in any wise affected by the test battery b when the terminal f is closed to ground or to aline as is done in the act of testing to determine the condition of a subscribers line, that is, to determine whether `two subscribers who were in connection have hung up their telephones.

As shown at board 2 the telephone lines of stations 1 and 2 are connected together by the plugs c d; these plugs are provided with metallic heel pieces so that when inserted so as to cover up the test piece of the spring jacks in which they are inserted the said test pieces will be extended electrically sothata test maybe made bymaking connection with the heels of the plugs. Thus suppose the lines of stations l and 2 have been connected` for considerable time and the clearing out annunciator has not been thrown down and the; operator wishes to find out whether the sub` tors telephone, this click being `due `to `the. closing of the circuit of battery a over the line of station l to the heel of plug c and thence through the plug f and cord e through the operators telephone to ground. Nowit is evident that if either telephone of two connected lines is off from the hookthe battery current from `the local battcryofsaid station will find circuit to the test plug and thence throughthe telephone when thetest is made at the heel of either of the two con necting plugs c CZ. Thus the `operator by means of the test `plug f may determine whethertwo connected subscribers havebotli hungup their telephones Without cutting in totheir circuit.

Either plug c cl may be usedin therstinf stance to test to determine whethera line is connected at anyother board. Supposetthe plugs c cl resting intheirsockets in `the key- `table and suppose a call sent in from `station 2throwing. down annunciator g the operator `at `board 2 thereupon inserts one of therplugs c d, we will say plug d, in the spring jack switch ofthe line of station 2 upon board 2 as shown; thecam lever of switch 7L being thrown down the operators telephone will :be connected with station 2 and theoperator may receive the order; suppose the order to beforllineof station l, the operator simply bytouching the tip of plug c to the frame or test pieceoflthe switch i, being the switch of the line of sta- `tion 1, upon board 2 and listening at hertele phone may determine whether the line called for is connected at any other of the boards; if the line is connected a cross will be established between the test circuit 7e and the line bytheplug where the connection is made, in which case a circuit will be formed through the operators telephone and battery b oven the test circuit la and the line tested andthe operator hearing the click caused in the telephone will know that the line is busy. The

battery b is of sufficient strength in itself to cause the click in the telephonewhen its circuit is thus completed. If, however, the telephone of the line tested is removed from its hook battery a `will be in the same circuit with battery b and the click heard in the telephone will therefore be louder. The experienced operator can therefore tell on making thetest not only whether the line tested is connected at another board but also can tell by the character of the sound whether the telephone line tested is being used in` conversation,that is, whether `the telephone of the line is removed from its hook. Of course it will be understood that if both telephones of two connected lines are removed from their hooks the two local batteries will be connected to send current in the same direction as battery t); the operator will not be able to tell whether one telephone or the other of two connected subscribers is removed from its switch; it may be one or the other, but generally will be both since both subscribers usually will hang up their telephones at the same time.

Having thus `described my invention, I claim as new and desire to secure by Letters Patent- 1. The combination withgtwdoiumore lines upon two `lor lmore switch boards,` each `line being connected witha` springjack upon each board, lof connecting plugs `and Ecords connected withLa l,listening key, theoperators telephone. outfit, a testing batterytconnected intermediate `of the listening `key and the operators telephone outfit, a test `plug and cord conncctedwithfthe operator-3s telephone outfit ata `point tbetweengthe test battery and telephoneouttit,.wherebya test may be made with the telephone outfitthrough the testbattery or indelendent of it as lnaylbe desired.

2. ,In t atelephone exchangesystenigthe combination withthe multipleswitch board system, of the subscribers transmitterfbattery connected with thetransmitten and in derived circuit ,with-the subscribers line and theoperators test battery connected ina direction to operate in conjunction with the subscribers transmitterbatterywhereby the operator maydetermine whethera line `is connected and by the sametest determine .whethenthe subscribers telephoneg-is removed from `the hook.

3. 1In a multiple switchboard syStem'the operators telephoneoutt, branches-through a test battery `tothe :listening keys and to a special `testing plug, subscribers telephone outfits having their batteriestin derived circuit through a transmitter .set `and to their 4respective individual lines, `whereby an; operator `may with the sametelephoneoutfitltest Vto determine whether a `line is connected at IOO In witness whereof I hereunto subscribe my name this 22d day of May, A. D. 1889.

CHARLES E. SCRIBNER.

Witnesses:

ELLA EDLER, GEORGE P. BARTON. 

